Pension for a resignee

I joined a nationalised bank's service in October 1967(roughly 2 years before nationalisation). I resigned from service in March 1986 on health grounds which was accepted as such. Years later in 1995 Pension regulations were introduced with retrospective effect from January 1986. However as per that minimum service for eligibility for pension is 20 years. I had served the bank only for 18 years and 5 months but resignation was the only way in which one could opt to exit the service in the year 1986. So bank disqualified me for pension eligibility on the ground that I had not completed 20 years of service. Be that as it may, in the year 2000, medical benefits were extended for retirees in which even those who resigned on health grounds were included. Accordingly I have been getting annual reimbursement of 2000 and I have fully availed life time hospitalisation benefit of ₹2 lakhs for me and my spouse. From 2015 I am also covered under wider insurance cover of ₹4 lakhs per annum and I have availed the benefits also. So can there be a dichotomy in bank's approach towards a resigned employee who resigned on health grounds - on the one hand, denying pension for reasons of minimum service requirements and on the other a compassionate approach for extending medical benefits as are available to the retirees? Cannot the pension regulations be amended to cover even resigness on health grounds? A pragmatic approach is the need of the hour. Can this forum throw light on possible flexibilities in this matter? Thanks and regards.